254 The Evolution of Agricultural Implements. 
Self-moving Engines . — For many years after its introduction 
the portable engine was drawn from place to place by horses, 
and, numerous as were the early patents taken out for traction 
engines, it was not till about 1860 that they won their way 
to the front. Boydell and Bray were conspicuous among the 
early workers in this field, the former fitting his wheels with 
an endless rail, and the latter with j>rojecting teeth, in the 
years 1854 and 1856 respectively. In 1859, Clayton and 
Shuttleworth, discarding all additions to the driving wheels, 
first showed the way to a practical traction engine, and intro- 
duced a design which has since been generally adopted. 
Self-moving engines have been greatly improved during 
recent years in three important particulars. In 1870, Messrs. 
Aveling and Porter prolonged the side-plates of the firebox 
upwards, forming these into brackets for carrying the bearings 
of the crank and counter-shafts, thus relieving the boiler from 
undue local strains. Previously to 1878, again, the gearing 
of self-moving engines had always been placed outside the crank 
brackets ; but in that year, for the first time, Messrs. Aveling and 
Porter succeeded in bringing all the wheels and pinions between 
the bearings, and the driving and side wheels close up to the 
side-plate brackets. By this arrangement the engine became 
greatly strengthened, its wear and tear correspondingly reduced, 
its width lessened, and its compactness increased. 
Within the last few years several patents have been taken 
out for traction-engine wheels with spring connections between 
the felloes and the tires. The object is to reduce wear and tear 
generally, and to prevent such vibrations as occur in passing 
over rough roads from materially affecting the depth at which 
the toothed wheels gear into one another. To judge fi’om the 
fact that spring wheels have suddenly become a favourite subject 
for patents with the chief makers of traction engines it seems 
probable that this innovation will soon be recognised as a 
valuable improvement. 
Messrs. John Fowler and Co.’s important contributions to 
the solution of the traction engine problem have already been 
indicated under the head of Steam Cultivation, to Avhich side of 
the question this firm’s attention has, from the first, been chiefly 
1 11 ned. 
Class VIII. — Dkainage Appliances. 
“Nothing,” said Mr. Coleman, reporting on the Royal Agri- 
cultural Society’s Show of 1881, “can be conceived of in the 
way of aid to suffering agriculture more valuable than a really 
efficient draining tool ; ” but this problem has yet to be resolved 
